Structural Design of Heavy-Lift Unmanned Cargo Drones in Low Altitudes

This chapter presents the conceptual loads analysis and the structural design of the unmanned cargo aircraft concepts within the Automated Low Altitude Air Delivery (ALAADy) project of the German Aerospace Center, DLR. Three concepts of a gyroplane, a fixed high-wing with a twin boom v-tail aircraft and a box wing aircraft are concerned in the project. The main focus is on the estimation of the structural weight of each unconventional aircraft configuration. However, the application of empirical formulations based on conventional aircraft configurations is not suitable for this task. Instead, the task is performed with a parametric design process which is designed to be used for the structural design of an unconventional aircraft. In this process, the structural models are set up as finite element models in a parametric manner. The loads analysis and the aeroelastic structural dimensioning are then performed using these finite element models. This process is developed by the DLR and it is called the MONA process. The major result of the process is the structural weight of each unmanned aircraft (UA) concept. Finally, the structural weights of all aircraft are compared. The weight comparison contributes to the global evaluation of the aircraft concepts within the ALAADY project. Based on the considered aircraft requirements, the considered load cases and the considered system masses, the gyroplane has the minimum structure weight of 2,720 kg.